The present invention relates to the field of aeroengines, e.g. turbojets, and it relates more particularly to a support structure interposed between the engine and the nacelle.
In known manner, in addition to providing a mechanical junction between the engine and the nacelle, such a support structure needs to ensure:                continuity of the airflow passage for the secondary (bypass) stream;        passages and supports for services (which may be electrical, mechanical, hydraulic) between the various components of the engine (core, fan, etc., . . . ) and the nacelle of the engine;        fire protection between the various compartments of the engine and the secondary stream; and        accessibility to pieces of equipment and to services for maintenance purposes.        
The support structure is constituted by a cylindrical frame that is sectorized (to have shroud sectors) and of narrow width (of the order of a few hundreds of millimeters along the axis of the engine), having covers that give easy access to the pieces of equipment they hide once the nacelle has been opened, and having a plurality of arms that are distributed regularly around the frame. Conventionally, the frame supports scoops of the air bleed system (booster variable bleed valves (VBVs)) and is designed to be fastened to the intermediate frame, which is itself constituted by a hub, a shroud, structural arms, and structural outlet guide vanes (OGVs).
With present-day technologies, the structural support has a fairing structure for giving access to pieces of equipment and also for reconstituting the airflow passage, such that its aerodynamic skin must also provide the assembly with mechanical strength. This leads to considerable weight since the aerodynamic surface of the support structure needs to be made of metal, generally as a casting given its complex shape, and it also needs to be relatively thick in order to be capable of being fabricated.
Since maintenance times need to be optimized, the present frame is seen as an obstacle to accessing pieces of equipment that it covers, which pieces of equipment must be capable of being removed, changed, verified, . . . during field maintenance, in a length of time that is limited and depends on the application, where the time required needs to take account of the time for disassembling and reassembling the frame itself.
There thus exists a need for a support structure is arranged more particularly between the hub of the intermediate casing and the shroud of the intermediate casing, and that enables easy access to be provided to such pieces of equipment (i.e. by improving time required to access them) while also providing a significant saving in weight and a reduction in the disturbances in the airflow passage.